I always keep the emergency flashers on the whole stop; I don't have an choice as our division directives state that they shall be on for the duration of the stop. I put the spot light on the rear-view mirror, and then shine my flashlight in the driver side mirror.
I don't generally use the passenger side approach on my initial approach because I'd the driver has a suspended operator's license the extraction of the driver gets tricky. I like to use passenger side approach on the reapproach to throw people off.
I generally air the stop right before I light up the driver or as I am initiating the stop. I'm lucky enough to have backup available within 30-45 seconds at any given time, so if my spidey sense starts to go off I air for an additional car immediately.